Heavy equipment has moved into the Sails Pavilion of the San Diego Convention Center, not for a trade show but to begin a $16 million replacement of the floor, roof and other repairs.

The project, due for completion in 2018, is part of $25.5 million in upgrades funded from a loan by the California Infrastructure and Economic Development Bank. Another $3.6 million in improvements is being covered by center operations and the city budget.

Convention officials showed off banks of LED lighting in the exhibit halls Tuesday, the first item on the to-do list to be completed and one of those funded locally.

“This is largest series of upgrades in convention center history,” said Laurie Coskey, chair of the San Diego Convention Center Corp. board.

Also planned are restroom upgrades, replacement of the ceiling and cooling towers in the west building, escalator and elevator modernization and fire safety retrofits.

Clifford “Rip” Rippetoe, the center’s president and CEO, said the improvements will help keep the facility competitive and environmentally sustainable.

But he said despite these improvements, some large conventions have decided to meet elsewhere, and others are considering a move because they need more space and expansion is on hold for legal and financial reasons.

Among conventions thinking of leaving is San Diego Comic-Con International, whose contract expires after the 2018 event. Rippetoe said negotiations are under way to extend the popular convention another three years.

However, he said he was not pessimistic about eventually seeking a tax increase, if that becomes necessary to finance an expansion. Voters rejected a tax increase to pay for a new Chargers stadium and convention center annex in November.

Previous plans called for a $520 million expansion but courts overturned the funding plan and lawsuits still remain that challenge a contiguous expansion on the waterfront.

Gil Cabrera, chairman of the board’s budget committee, said the old plans would have to be radically changed because a $270 million, 831-room hotel, known as Fifth Avenue Landing, has been approved on part of the expansion site west of the convention center.

One possibility, he said, is to share meeting space with the hotel. Expanding the exhibit halls would be more difficult because loading docks would have to be relocated and there is limited space to do that.

The convention center opened in 1989 and the rooftop meeting area was enclosed a few years later by a fabric structure when convention planners said they could not count on San Diego weather to be rain-free. The facility was last expanded in 2001.

Officials said the roof fabric has lasted longer than its original 20-year useful life, but they hope its replacement will last up to 40 years due to technical improvements.

Meanwhile, the concrete floor has been deteriorating and officials showed off the construction site, where T.B. Penick construction crews are digging up 4 inches of concrete and 3 inches of foam before replacement. The $3.6 million replacement is expected to be finished in March. The pavilion will close in August for a six-month replacement of the fabric roof.

The IBank loan previously was described as carrying an interest rate of 3.59 percent and an annual payment up to $1.6 million over its 25-year life.

Previously, the agency loaned $21.5 million to three other projects in the county: $1.8 million to an Oceanside community center in 2001; $3.5 million to Del Mar for a sewage collection and treatment plant; and another $16.2 million to Del Mar for a new city hall. The convention center project is the largest approved so far under its revolving fund program and slightly exceeded the standard $25 million maximum.